/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 */

package org.apache.iotdb.db.mpp.plan.planner.plan.node.process;

import org.apache.commons.lang3.Validate;
import org.apache.iotdb.db.mpp.plan.planner.plan.node.PlanNode;
import org.apache.iotdb.db.mpp.plan.planner.plan.node.PlanNodeId;
import org.apache.iotdb.db.mpp.plan.planner.plan.node.PlanNodeType;
import org.apache.iotdb.db.mpp.plan.planner.plan.node.PlanVisitor;
import org.apache.iotdb.db.mpp.plan.planner.plan.parameter.CrossSeriesAggregationDescriptor;
import org.apache.iotdb.db.mpp.plan.planner.plan.parameter.GroupByTimeParameter;
import org.apache.iotdb.db.mpp.plan.statement.component.Ordering;
import org.apache.iotdb.tsfile.utils.ReadWriteIOUtils;

import javax.annotation.Nullable;
import java.io.DataOutputStream;
import java.io.IOException;
import java.nio.ByteBuffer;
import java.util.*;
import java.util.Map.Entry;
import java.util.stream.Collectors;

public class GroupByTagNode extends MultiChildProcessNode {

    private final List<String> tagKeys;
    private final Map<List<String>, List<CrossSeriesAggregationDescriptor>>
            tagValuesToAggregationDescriptors;
    private final List<String> outputColumnNames;

    // The parameter of `group by time`.
    // Its value will be null if there is no `group by time` clause.
    @Nullable
    protected GroupByTimeParameter groupByTimeParameter;

    protected Ordering scanOrder;

    public GroupByTagNode(
            PlanNodeId id,
            List<PlanNode> children,
            @Nullable GroupByTimeParameter groupByTimeParameter,
            Ordering scanOrder,
            List<String> tagKeys,
            Map<List<String>, List<CrossSeriesAggregationDescriptor>> tagValuesToAggregationDescriptors,
            List<String> outputColumnNames) {
        super(id, children);
        this.groupByTimeParameter = groupByTimeParameter;
        this.scanOrder = Validate.notNull(scanOrder);
        this.tagKeys = Validate.notNull(tagKeys);
        this.tagValuesToAggregationDescriptors = Validate.notNull(tagValuesToAggregationDescriptors);
        this.outputColumnNames = Validate.notNull(outputColumnNames);
    }

    public GroupByTagNode(
            PlanNodeId id,
            @Nullable GroupByTimeParameter groupByTimeParameter,
            Ordering scanOrder,
            List<String> tagKeys,
            Map<List<String>, List<CrossSeriesAggregationDescriptor>> tagValuesToAggregationDescriptors,
            List<String> outputColumnNames) {
        super(id);
        this.groupByTimeParameter = groupByTimeParameter;
        this.scanOrder = Validate.notNull(scanOrder);
        this.tagKeys = Validate.notNull(tagKeys);
        this.tagValuesToAggregationDescriptors = Validate.notNull(tagValuesToAggregationDescriptors);
        this.outputColumnNames = Validate.notNull(outputColumnNames);
    }

    @Override
    public PlanNode clone() {
        // TODO: better do deep copy
        return new GroupByTagNode(
                getPlanNodeId(),
                this.groupByTimeParameter,
                this.scanOrder,
                this.tagKeys,
                this.tagValuesToAggregationDescriptors,
                this.outputColumnNames);
    }

    @Override
    public List<String> getOutputColumnNames() {
        List<String> ret = new ArrayList<>(tagKeys);
        ret.addAll(outputColumnNames);
        return ret;
    }

    @Override
    public <R, C> R accept(PlanVisitor<R, C> visitor, C context) {
        return visitor.visitGroupByTag(this, context);
    }

    @Override
    protected void serializeAttributes(ByteBuffer byteBuffer) {
        // Plan type.
        PlanNodeType.GROUP_BY_TAG.serialize(byteBuffer);

        // Tag keys.
        ReadWriteIOUtils.writeStringList(tagKeys, byteBuffer);

        // Tag values to aggregation descriptors.
        ReadWriteIOUtils.write(tagValuesToAggregationDescriptors.size(), byteBuffer);
        for (Entry<List<String>, List<CrossSeriesAggregationDescriptor>> entry :
                tagValuesToAggregationDescriptors.entrySet()) {
            ReadWriteIOUtils.writeStringList(entry.getKey(), byteBuffer);
            ReadWriteIOUtils.write(entry.getValue().size(), byteBuffer);
            for (CrossSeriesAggregationDescriptor aggregationDescriptor : entry.getValue()) {
                if (aggregationDescriptor == null) {
                    ReadWriteIOUtils.write((byte) 0, byteBuffer);
                } else {
                    ReadWriteIOUtils.write((byte) 1, byteBuffer);
                    aggregationDescriptor.serialize(byteBuffer);
                }
            }
        }

        // Output column names.
        ReadWriteIOUtils.writeStringList(outputColumnNames, byteBuffer);

        // Group by time parameter.
        if (groupByTimeParameter == null) {
            ReadWriteIOUtils.write((byte) 0, byteBuffer);
        } else {
            ReadWriteIOUtils.write((byte) 1, byteBuffer);
            groupByTimeParameter.serialize(byteBuffer);
        }

        // Scan order.
        ReadWriteIOUtils.write(scanOrder.ordinal(), byteBuffer);
    }

    @Override
    protected void serializeAttributes(DataOutputStream stream) throws IOException {
        // Plan type.
        PlanNodeType.GROUP_BY_TAG.serialize(stream);

        // Tag keys.
        ReadWriteIOUtils.writeStringList(tagKeys, stream);

        // Tag values to aggregation descriptors.
        ReadWriteIOUtils.write(tagValuesToAggregationDescriptors.size(), stream);
        for (Entry<List<String>, List<CrossSeriesAggregationDescriptor>> entry :
                tagValuesToAggregationDescriptors.entrySet()) {
            ReadWriteIOUtils.writeStringList(entry.getKey(), stream);
            ReadWriteIOUtils.write(entry.getValue().size(), stream);
            for (CrossSeriesAggregationDescriptor aggregationDescriptor : entry.getValue()) {
                if (aggregationDescriptor == null) {
                    ReadWriteIOUtils.write((byte) 0, stream);
                } else {
                    ReadWriteIOUtils.write((byte) 1, stream);
                    aggregationDescriptor.serialize(stream);
                }
            }
        }

        // Output column names.
        ReadWriteIOUtils.writeStringList(outputColumnNames, stream);

        // Group by time parameter.
        if (groupByTimeParameter == null) {
            ReadWriteIOUtils.write((byte) 0, stream);
        } else {
            ReadWriteIOUtils.write((byte) 1, stream);
            groupByTimeParameter.serialize(stream);
        }

        // Scan order.
        ReadWriteIOUtils.write(scanOrder.ordinal(), stream);
    }

    @Nullable
    public GroupByTimeParameter getGroupByTimeParameter() {
        return groupByTimeParameter;
    }

    public Ordering getScanOrder() {
        return scanOrder;
    }

    public List<String> getTagKeys() {
        return tagKeys;
    }

    public Map<List<String>, List<CrossSeriesAggregationDescriptor>>
    getTagValuesToAggregationDescriptors() {
        return tagValuesToAggregationDescriptors;
    }

    public static GroupByTagNode deserialize(ByteBuffer byteBuffer) {
        // Tag keys.
        List<String> tagKeys = ReadWriteIOUtils.readStringList(byteBuffer);

        // Tag values to aggregation descriptors.
        int numOfEntries = ReadWriteIOUtils.readInt(byteBuffer);
        Map<List<String>, List<CrossSeriesAggregationDescriptor>> tagValuesToAggregationDescriptors =
                new HashMap<>();
        while (numOfEntries > 0) {
            List<String> tagValues = ReadWriteIOUtils.readStringList(byteBuffer);
            List<CrossSeriesAggregationDescriptor> aggregationDescriptors = new ArrayList<>();
            int numOfAggregationDescriptors = ReadWriteIOUtils.readInt(byteBuffer);
            while (numOfAggregationDescriptors > 0) {
                byte isNotNull = ReadWriteIOUtils.readByte(byteBuffer);
                if (isNotNull == 1) {
                    aggregationDescriptors.add(CrossSeriesAggregationDescriptor.deserialize(byteBuffer));
                }
                numOfAggregationDescriptors -= 1;
            }
            tagValuesToAggregationDescriptors.put(tagValues, aggregationDescriptors);
            numOfEntries -= 1;
        }

        // Output column names.
        List<String> outputColumnNames = ReadWriteIOUtils.readStringList(byteBuffer);

        // Group by time parameter.
        byte hasGroupByTimeParameter = ReadWriteIOUtils.readByte(byteBuffer);
        GroupByTimeParameter groupByTimeParameter = null;
        if (hasGroupByTimeParameter == 1) {
            groupByTimeParameter = GroupByTimeParameter.deserialize(byteBuffer);
        }

        // Scan order.
        Ordering scanOrder = Ordering.values()[ReadWriteIOUtils.readInt(byteBuffer)];

        PlanNodeId planNodeId = PlanNodeId.deserialize(byteBuffer);
        return new GroupByTagNode(
                planNodeId,
                groupByTimeParameter,
                scanOrder,
                tagKeys,
                tagValuesToAggregationDescriptors,
                outputColumnNames);
    }

    @Override
    public boolean equals(Object o) {
        if (this == o) {
            return true;
        }
        if (o == null || getClass() != o.getClass()) {
            return false;
        }
        if (!super.equals(o)) {
            return false;
        }
        GroupByTagNode that = (GroupByTagNode) o;
        return Objects.equals(groupByTimeParameter, that.groupByTimeParameter)
                && scanOrder == that.scanOrder
                && Objects.equals(tagKeys, that.tagKeys)
                && Objects.equals(tagValuesToAggregationDescriptors, that.tagValuesToAggregationDescriptors)
                && Objects.equals(outputColumnNames, that.outputColumnNames);
    }

    @Override
    public int hashCode() {
        return Objects.hash(
                super.hashCode(),
                groupByTimeParameter,
                scanOrder,
                tagKeys,
                tagValuesToAggregationDescriptors,
                outputColumnNames);
    }

    @Override
    public String toString() {
        return String.format(
                "GroupByTagNode-%s: Output: %s, Input: %s",
                getPlanNodeId(),
                getOutputColumnNames(),
                tagValuesToAggregationDescriptors.values().stream()
                        .flatMap(
                                list -> list.stream().map(CrossSeriesAggregationDescriptor::getInputExpressions))
                        .collect(Collectors.toList()));
    }
}
